v8: add cpu profile APIs

Author: theanarkh

lib/v8.js

@@ -27,6 +27,7 @@ const {
   Int8Array,
   JSONParse,
   ObjectPrototypeToString,
+  SymbolDispose,
   Uint16Array,
   Uint32Array,
   Uint8Array,
@@ -112,6 +113,8 @@ const binding = internalBinding('v8');
 const {
   cachedDataVersionTag,
   setFlagsFromString: _setFlagsFromString,
+  startCpuProfile: _startCpuProfile,
+  stopCpuProfile: _stopCpuProfile,
   isStringOneByteRepresentation: _isStringOneByteRepresentation,
   updateHeapStatisticsBuffer,
   updateHeapSpaceStatisticsBuffer,
@@ -166,6 +169,31 @@ function setFlagsFromString(flags) {
   _setFlagsFromString(flags);
 }
 
+class CPUProfileHandle {
+  #id = null;
+
+  constructor(id) {
+    this.#id = id;
+  }
+
+  stop() {
+    return _stopCpuProfile(this.#id);
+  };
+
+  [SymbolDispose]() {
+    this.stop();
+  }
+}
+
+/**
+ * Starting CPU Profile.
+ * @returns {CPUProfileHandle}
+ */
+function startCpuProfile() {
+  const id = _startCpuProfile();
+  return new CPUProfileHandle(id);
+}
+
 /**
  * Return whether this string uses one byte as underlying representation or not.
  * @param {string} content
@@ -478,4 +506,5 @@ module.exports = {
   setHeapSnapshotNearHeapLimit,
   GCProfiler,
   isStringOneByteRepresentation,
+  startCpuProfile,
 };

src/node_v8.cc

@@ -28,13 +28,18 @@
 #include "node_external_reference.h"
 #include "util-inl.h"
 #include "v8.h"
+#include "v8-profiler.h"
 
 namespace node {
 namespace v8_utils {
 using v8::Array;
 using v8::BigInt;
 using v8::CFunction;
 using v8::Context;
+using v8::CpuProfile;
+using v8::CpuProfiler;
+using v8::CpuProfilingResult;
+using v8::CpuProfilingStatus;
 using v8::FunctionCallbackInfo;
 using v8::FunctionTemplate;
 using v8::HandleScope;
@@ -47,6 +52,8 @@ using v8::Local;
 using v8::LocalVector;
 using v8::MaybeLocal;
 using v8::Name;
+using v8::NewStringType;
+using v8::Number;
 using v8::Object;
 using v8::ScriptCompiler;
 using v8::String;
@@ -243,6 +250,36 @@ void SetFlagsFromString(const FunctionCallbackInfo<Value>& args) {
   V8::SetFlagsFromString(*flags, static_cast<size_t>(flags.length()));
 }
 
+void StartCpuProfile(const FunctionCallbackInfo<Value>& args) {
+  Environment* env = Environment::GetCurrent(args);
+  Isolate* isolate = env->isolate();
+  CpuProfilingResult result = env->StartCpuProfile();
+  if (result.status == CpuProfilingStatus::kErrorTooManyProfilers) {
+    return THROW_ERR_CPU_PROFILE_TOO_MANY(isolate, "There are too many CPU profiles");
+  } else if (result.status == CpuProfilingStatus::kStarted) {
+    args.GetReturnValue().Set(Number::New(isolate, result.id));
+  }
+}
+
+void StopCpuProfile(const FunctionCallbackInfo<Value>& args) {
+  Environment* env = Environment::GetCurrent(args);
+  Isolate* isolate = env->isolate();
+  CHECK(args[0]->IsUint32());
+  uint32_t profile_id = args[0]->Uint32Value(env->context()).FromJust();
+  CpuProfile* profile = env->StopCpuProfile(profile_id);
+  if (!profile) {
+    return THROW_ERR_CPU_PROFILE_NOT_STARTED(isolate, "CPU profile not started");
+  }
+  auto json_out_stream = std::make_unique<node::JSONOutputStream>();
+  profile->Serialize(json_out_stream.get(),
+                     CpuProfile::SerializationFormat::kJSON);
+  profile->Delete();
+  Local<Value> ret;
+  if (ToV8Value(env->context(), json_out_stream->out_stream().str(), isolate).ToLocal(&ret)) {
+    args.GetReturnValue().Set(ret);
+  }
+}
+
 static void IsStringOneByteRepresentation(
     const FunctionCallbackInfo<Value>& args) {
   CHECK_EQ(args.Length(), 1);
@@ -682,6 +719,9 @@ void Initialize(Local<Object> target,
   // Export symbols used by v8.setFlagsFromString()
   SetMethod(context, target, "setFlagsFromString", SetFlagsFromString);
 
+  SetMethod(context, target, "startCpuProfile", StartCpuProfile);
+  SetMethod(context, target, "stopCpuProfile", StopCpuProfile);
+
   // Export symbols used by v8.isStringOneByteRepresentation()
   SetFastMethodNoSideEffect(context,
                             target,
@@ -726,6 +766,8 @@ void RegisterExternalReferences(ExternalReferenceRegistry* registry) {
   registry->Register(GetCppHeapStatistics);
   registry->Register(IsStringOneByteRepresentation);
   registry->Register(fast_is_string_one_byte_representation_);
+  registry->Register(StartCpuProfile);
+  registry->Register(StopCpuProfile);
 }
 
 }  // namespace v8_utils

src/node_v8.h

@@ -10,7 +10,7 @@
 #include "node_snapshotable.h"
 #include "util.h"
 #include "v8.h"
-
+#include "node_errors.h"
 namespace node {
 class Environment;
 struct InternalFieldInfoBase;

test/parallel/test-v8-cpu-profile.js

@@ -0,0 +1,15 @@
+'use strict';
+require('../common');
+const assert = require('assert');
+const v8 = require('v8');
+
+{
+  const handle =  v8.startCpuProfile();
+  JSON.parse( handle.stop());
+  assert.throws(() => handle.stop(), { code: "ERR_CPU_PROFILE_NOT_STARTED" });
+}
+
+{
+  // It will be stopped automatically when process exits
+  v8.startCpuProfile();
+}